Interspecies (human sperm/hamster ova) in vitro fertilization test results were compared with pregnancies and other clinical data of couples consulting a fertility clinic. Initial data confirm this test to be a valid and useful adjunct to semen analysis as tests of male fertility. The demonstrated cryopreservation of both sperm and ova greatly extends the scope of this test. A model computer program to analyze reproductive changes related to environmental factors is being established.